Intraoperative endocardial and epicardial ablation probe

ABSTRACT

An elongate, malleable ablation probe including an elongate malleable body and a plurality of longitudinally spaced apart electrodes disposed at a distal end thereof. The electrodes are separated one from another by insulative material. In one embodiment, a malleable insert is provided for insertion into a flexible longitudinal sleeve, the flexible longitudinal sleeve conforming to the shape of the malleable insert upon such insertion. In other embodiments, a malleable core is surrounded by a flexible body, the electrodes being mounted to the body.

RELATED APPLICATION

This patent application is a divisional application of application Ser.No. 10/396,231, which is a divisional application of application Ser.No. 09/485,361 (now U.S. Pat. No. 6,540,742) entitled AN INTRAOPERATIVEENDOCARDIAL AND EPICARDIAL ABLATION PROBE, filed on 28 JANUARY 2000 inthe names of Thomas et al, which application is commonly assigned withpresent application and incorporated herein in its entirety by thisreference.

The present invention relates to a method and apparatus for mapping andablating tissue, and in particular to a malleable, shapeable probe forproducing elongated linear lesions in tissue.

BACKGROUND

It is known that tissue, including damaged myocardial tissue, can beablated by the application of radio frequency energy thereto viaconductive electrodes embodied in a probe structure. RF ablation oftissue is commonly used in an attempt to remove myocardial defects,tumours, portions of tissue mass, and the like. RF ablation can be usedto treat cardial disfunctions such as ventricular arrhythmia, atrialflutter, atrial fibrillation, ventricular tachycardia and the like.

Such disorders involve abnormal heart muscles causing abnormal activityof the electrical signals that are generated to create musclecontraction. One result of this abnormal electrical activity in theatrial part of the heart muscle may be an irregular heartbeat. A commonfeature of atrial fibrillation is impaired atrial contraction. The heartbeat rate may also be increased.

Electrode catheters are commonly used to effect RF ablation of tissue toremove or otherwise interrupt the abnormal electrical activity caused bydefective myocardial tissue.

FIG. 1 is a schematic diagram illustrating such a catheter 10. Thecatheter 10 is typically made of a highly flexible plastic or rubbertube 14. At the distal end of the catheter body 14 are located a numberof metal electrodes 12 for delivering RF energy. The conventionalcatheter probe utilises ring-like electrodes concentrically arrangedaround the catheter body 14. Alternatively, the catheter probe 10 aloneor in combination with the ring-like electrodes may have a singleelectrode at the tip of the distal end of the catheter 10. The catheterbody 14 includes a number of internal electrical conductors (not shown)connected to respective ones of the electrodes 12 at one end. Theconductors can be connected at an opposite end of the catheter 10 to asource of RF energy and other equipment. The RF energy is delivered viathe conductors to the electrodes 12.

In use, such a catheter probe 10 is inserted via an incision in apatient's body into a blood vessel, such as a vein, and the catheter isthen manoeuvred through the blood vessel to the patient's heart. Thus,the electrodes 12 at the distal end of the catheter 10 can be insertedinto an interior chamber of a patient's heart to ablate endocardialtissue. FIG. 2 is a simplified schematic diagram illustrating thecatheter 10 disposed within a portion of an atrium 20. A defectiveportion of the myocardial tissue is detected by mapping electricalactivity in the myocardial tissue, and then applying RF energy via oneor more of the electrodes 12 adjacent to the defective portion.

A significant disadvantage of conventional catheter ablation is that,due to the very flexible nature of the catheter itself, it is difficultto accurately position and maintain the positioning of the electrodesrelative to a portion of myocardial tissue. This is disadvantageous inthat movement and imprecise placement of the catheter can resultundesirably in the ablation or destruction of healthy tissue, while atthe same time the tissue sought-to-be ablated may not have been ablated,thereby requiring further ablation.

As will be understood from FIG. 2, due to the readily flexible nature ofthe catheter body 14 and its limited ability to retain any particularform, the catheter 10 is difficult to position at a desired location,and often does not adequately conform to the tissue surface. As shown inFIG. 2, due to contact with a far wall of the atrium, the catheter body14 flexes upwardly from its insertion at left into the atrial chamberand is then bent downwardly at its distal end by the irregularity 22 inthe myocardial tissue of the atrium 20. Due to the way in which thecatheter 10 is bent and its imprecise positioning, only a small portionof the distal end of the catheter 10 contacts the tissue at location 22.In fact, only a small portion of the third electrode contacts thedefective, irregularly shaped tissue 22.

Another disadvantage of such catheter probes 10 is that they aredirected to ablating focal defects, where only a portion of an electrodein contact with the tissue produces a “spot” or pointlike lesion in thetissue.

A further catheter ablation probe has been proposed using the same typeof highly flexible catheter structure in combination with an externalguide wire provided between the distal end and an intermediate point ofthe catheter probe. The guide wire can be tightened or released so as tocontrol arcuate flexing of a sequence of band-like electrodes arrangedalong the catheter. However, this probe is also disadvantageous in thatmovement and placement of the catheter is still imprecise and theelectrodes may not have good contact with irregular surfaces to beablated. Still further, the ring-like electrodes of such a catheterprobe also produce a “spot” or pointlike lesion in the tissue.

Thus, conventional catheter probes have a number of significantdisadvantages. Firstly, the electrodes of the probe are directed toproducing spot or pointlike lesions in tissue. Secondly, due to thehighly flexible nature of the catheter body, it is difficult tomanoeuvre and accurately position and retain the position of theelectrodes of the catheter at any position. Thirdly, again due to thevery flexible nature of the catheter typically made of soft, bendableplastic, or rubber like substances, the distal end of the catheter doesnot readily conform to irregularly shaped surfaces of tissue.Accordingly, a need clearly exists for a probe capable of overcoming oneor more disadvantages of conventional devices.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides an elongate, malleableablation probe including:

an elongate malleable body; and

a plurality of longitudinally spaced apart electrodes disposed at adistal end of said malleable body, said electrodes being separated onefrom another by insulative material.

Preferably, the electrodes are flat and are arranged linearly along saidprobe.

In a second aspect, the present invention provides a probe for ablatingtissue, including:

an elongate, bendable body;

a plurality of substantially flat spaced apart electrodes linearlyarranged along a longitudinal extent of said body and connected with asurface of said body;

insulative material separating said spaced apart electrodes one fromanother;

a plurality of electrical conductors, wherein at least one of saidplurality of conductors is connected to each respective one of theplurality of electrodes; and

a malleable core disposed within said elongate body, whereby said probeis deformable and is able to retain a shape formed by bending saidprobe.

In a third aspect, the present invention provides a probe for ablatingof tissue, comprising:

a tubular body of bendable material defining an elongate cavity;

a plurality of flat electrodes linearly arranged along the longitudinalextent of said tubular body;

insulative portions separating said electrodes from each other;

a plurality of electrical conductors, at least one of which is connectedwith each respective one of said plurality of electrodes; and

an insert member having a predefined shape for insertion into theelongate cavity of said tubular body, wherein said tubular body conformsto the predefined shape upon insertion of the insert member into theelongate cavity.

In a fourth aspect, the present invention provides a probe for ablatingtissue, comprising:

an elongate body of bendable material, wherein said body has asubstantially flat surface extending along a longitudinal extent of adistal end of said body;

a plurality of flat electrodes arranged in a linear configuration onsaid flat surface of said body in a predetermined spaced apartrelationship to each other;

insulative material separating said flat electrodes one from another;

a plurality of conductors, wherein at least one conductor is connectedwith each respective one of said plurality of electrodes; and

a malleable core formed in said body, wherein said probe is deformable.

Preferably, in each of the above aspects of the invention, one or moreprongs are connected with each electrode, wherein the one or more prongsis used to puncture the body and is capable of being bent.

Preferably, a temperature sensing device is connected to at least oneelectrode. Still further, at least two conductors of the plurality ofconductors are connected to the electrode, and one of the conductorscomprises a thermocouple as the temperature sensing device.

Still further, in each of the above aspects, the body is preferably madeof insulative material.

In a fifth aspect, the present invention provides a method of ablatingtissue, said method comprising the steps of:

deforming an elongated, malleable ablation probe to conform to anirregular surface of said tissue, wherein said probe comprises a lineararrangement of flat electrodes separated one from another by insulativematerial along a longitudinal extent of said probe; and

ablating said tissue using one or more of said electrodes contactingsaid tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described hereinafter, by wayof example only, with reference to the drawings, in which:

FIG. 1 is a perspective view of a conventional catheter probe;

FIG. 2 is a side elevation view of the catheter probe of FIG. 1 duringuse;

FIG. 3 is a bottom plan view of a hand-held surgical deviceincorporating an RF ablation probe according to the invention;

FIG. 4 is top plan view of the device of FIG. 3;

FIG. 5 is a right side elevation view of the device of FIG. 3;

FIGS. 6A and 6B are sectional, side elevation and cross-sectional, frontelevation views of the RF ablation probe according to the embodiments ofthe invention, generally, and in particular the embodiment shown in FIG.3;

FIGS. 7A to 7D illustrate the use of the RF ablation probe shown in FIG.3 to septate myocardial tissue;

FIGS. 8, 9 and 10 are side elevation, top plan and cross-sectional frontviews of a second embodiment of an RF ablation probe according to theinvention;

FIGS. 11, 12 and 13 are side elevation, cross-sectional front, andsectional, side elevation views of a third embodiment of an RF ablationprobe according to the invention; and

FIGS. 14 and 15 are side elevation and top plan views of a fourthembodiment of an RF ablation probe according to a the invention.

DETAILED DESCRIPTION

Overview

The embodiments of the invention are directed to probes for ablatingtissue to produce lesions, and in particular, to producing elongatedlinear lesions. The embodiments of the present invention areparticularly useful for producing thin linear lesions of epicardial andendocardial tissue to septate the tissue, creating “corridors” toinhibit, minimise or eliminate reentrant pathways in such tissue. Thefirst, second and third embodiments are particularly advantageous inthat the probes have a structure enabling them to be readily and easilyshaped to conform to the contour and/or irregularities of the surface ofa tissue body.

The probe has a “memory” capability and will retain its shape when bent.In this way, the probe can be plastically deformed to substantiallycomplement the shape of an irregular surface. In the followingdescription, numerous specific details such as conductive materials forelectrodes, specific types of tubing and fillers for probe bodies,specific malleable or plastically deformable materials for providing theabove noted memory capability, etc. are described in detail to provide amore thorough description of the present invention. However, it will beapparent to one skilled in the art that the present invention may bepracticed in other embodiments which do not employ the same specificdetails. Furthermore, well-known and understood aspects and featureshave not been described in detail so as not to unnecessarily obscure thepresent invention.

FIRST EMBODIMENT

A hand-held surgical device 34 incorporating a first embodiment radiofrequency (RF) ablation probe according to the invention is illustratedin FIGS. 3 to 6. The probe has a malleable tip capable of being bent ordeformed and maintaining the shaped configuration thus provided. Toeffect this, an elongate insulative body 38 of electrically andthermally insulative material is provided with a malleable core 44,preferably made of a soft metal such as copper and disposed within theinsulative body 38.

A linear arrangement of spaced-apart flat electrodes 40 is disposedalong the length of one surface of the elongated, insulative body 38 atits distal end. In the embodiment shown, the insulative body 38 istubular in form and comprises flexible, bendable plastics or rubbermaterial. One or more electrical leads or conductors 42 are connected toeach of the electrodes 40 to deliver RF energy from a remote source.Preferably, the conductors 42 pass through the interior of theinsulative probe body 38. Further, the electrical conductors 42 may beused to couple electrical signals from the electrodes to one or moreremote devices connected at the opposite end of the probe, for example,to implement mapping of electrical activity in the myocardium.

This configuration and assembly of an RF ablation probe is particularlyadvantageous in that it is readily capable of being shaped andconfigured so that the linear arrangement of flat electrodes complementsthe contour and irregularities of a tissue body to be ablated. Inparticular, the probe can be readily shaped manually by a surgeon toconform to the surface of myocardial tissue and structures observedduring surgery. The bendable, malleable characteristics of the RFablation probe are provided by the malleable core member of the probe sothat the probe is adaptable to variously shaped surfaces and has amemory capability to retain its formed shape.

FIG. 4 illustrates a top plan view of the hand-held surgical device 30including the probe structure 38 with the electrodes 40. The handle 34is connected at one end by an electrical cable 32 to remote equipment(not shown), including an RF energy generator. Mapping equipment canalso be connected to the probe. Temperature control equipment can alsobe connected to the probe for optimal functioning. The other end of thehandle 34 has the adaptable malleable RF ablation probe 38, 40 extendingtherefrom. The probe body 38 has a number of the flat electrodes 40linearly arranged in the upper surface thereof in a predetermined spacedapart relationship. Preferably, the probe has four rectangular flatelectrodes 40. However, differing numbers of electrodes, e.g., 3, 5,etc, can be practiced without departing from the scope and spirit of theinvention. The arrangement, shape and number of electrodes can beselected to produce elongated lesions of 1 to 10 cm. The long flat shapeof the electrodes 40 maximises tissue contact while minimising thethermal momentum of each electrode. The small thickness and low mass ofthe electrodes 40 allow a respective temperature sensing device such asa thermistor or thermocouple associated with the electrode 40 to measurethe true tissue temperature with relative accuracy.

As shown in FIG. 3, the handle of the hand-held device 34 alsoincorporates a button switch 36 which can be actuated to deliver RFenergy to one or more of the electrodes 40 via internal conductors 42.While the upper surface of each electrode 40 is flat, a side elevationview of FIG. 5 illustrates that in this embodiment a number of thin legsare preferably provided on both longitudinal edges of the electrodes 40.Using such legs, the substantially flat electrode 40 on the uppersurface of the probe body 38 can be crimped or otherwise fastenedthereto. The terminal ends of the crimping legs shown in FIG. 3 aregenerally indicated by the bracket with reference numeral 40.

This embodiment of the invention may be practiced using crimping alone,or in combination with bio-compatible adhesives such as a two-componentepoxy resin. The respective under-surfaces of the electrodes 40 can beadhered to the insulative body 38 using such an epoxy resin. The epoxyresin should have a suitable binding strength that remains stablebetween body temperature and 120° C., if crimping and other mechanicalfastening techniques are to be avoided. In the light of the foregoing,it will be apparent to those skilled in the art that other methods offastening or incorporating electrodes in an insulative body well-knownto such persons can be practiced without departing from the scope andspirit of the present invention.

The electrodes 40 must be electrically conductive, and preferably aremade of metal. Still further, in the embodiment shown, the electrodes 40are made of stainless steel. However, it will be apparent to one skilledin the art that other materials having high electrical conductivity andcapable of withstanding temperatures between room temperature and about120° C. can be used without departing from the scope and spirit of theinvention.

FIG. 5 indicates that the RF ablation probe 38, 40 can be bent, adapted,shaped or otherwise deformed or deflected as indicated by the arrow inthe side elevation view. In particular, the distal end of the probe body38 having the four electrodes 40 is curved downwardly relative to theposition shown in the top plan view of FIG. 4. In this embodiment, thestainless steel electrodes 40 incorporated in the distal end of theprobe 38 each preferably have dimensions of 4 mm×2.5 mm, with a spacingof 4 mm between each pair of electrodes 40. Thus, the electrodes 40 havea thin, flat, substantially rectangular form. The malleable tip maypreferably be 3 to 6 cm in length. However, other sizes and shapes ofelectrodes and spacing therebetween may be practiced without departingfrom the scope and spirit of the invention. Smaller electrodes withequally smaller spacing therebetween may be practiced, thereby offeringincreased bendability to the probe structure. For example, small squareelectrodes of 2.5×2.5 mm with inter-electrode distances of 2.5 mm orless may be practiced.

FIGS. 6A and 6B are sectional side elevation and cross-sectional frontelevation views, respectively, of the probe 38, 40 of FIGS. 3 to 5. Tosimplify the drawing, the crimping legs extending from each of the fourelectrodes 40 are not illustrated. The malleable member is a copper core44 included within the insulative body 38 that runs lengthwise along thelongitudinal extent of the probe 38. Arranged along the upper flatsurface of the insulative body 38 are four rectangular electrodes 40.Preferably, each flat electrode 40 has a thermocouple or othertemperature sensing device connected therewith for measuring thetemperature of the electrode 40. Thus, one of the electrical leads 42may be made of a metal conductor such as stainless steel, while theother lead comprises a thermocouple, such as nickel. Alternatively, athermistor can be connected to the electrode 40 as the temperaturesensing device. In each case, the electrical lead(s) 42 is fixedlyconnected to a respective electrode 40, and this is preferably done byspot welding. As indicated in FIG. 6B, the upper surface of theinsulative probe body 38 is preferably flat and the electrodes 40 (e.g.,40A) are likewise flat.

This embodiment of the invention is made by affixing, preferably usingan epoxy resin, the flat electrodes 40 to an upper surface of theinsulative plastics or rubber-like, hollow tubing 38 and then spotwelding each pair of electrical conductors 42 to the respectiveelectrode 40. This welding also serves to increase the mechanicalstrength binding the electrodes 40 to the body 38. The malleable memberor core 44 is provided in the hollow interior of the tubular body 38.The crimping legs shown in FIGS. 3 and 5, are then crimped to securelybind the elements 38, 40, 44 together. In an alternative configuration,prior to crimping of legs, the hollow interior containing the electricalleads 42 and the malleable core 44 can be filled with an insulative,rubbery material such as SILASTIC (trade mark) to form a solid matrix.

While the first embodiment of the invention has been described withreference to electrodes formed and bound to the probe body by affixingusing adhesive and crimping, it will be readily apparent to one skilledin the art that other techniques can be practiced without departing fromthe scope and spirit of the invention. Further, rather than affixing orcrimping the electrode to an insulative body, where the body itselfprovides the insulation between electrodes, the insulative portion(s)may be applied separately by, for example, spray coating and siliconlayer.

Use of the First Embodiment

FIGS. 7A to 7D illustrate an exemplary use of the malleable ablationprobe 38, 40 to produce linear lesions. To septate an interior surfaceof the right atrium 96, a small cut 94 is made into the myocardialtissue. A surgeon then illuminates the aperture using a light 92 andobserves the interior surfaces of the chamber. Having observed thesurface to be ablated, the surgeon shapes, bends or otherwise deformsthe RF ablation probe 38, 40 SO that the malleable tip containing theelectrodes 40 conforms with the surface to be ablated. The surgeon cantest fit the tip and remove it for minor shape adjustments until asatisfactorily complementary fit is achieved between the tip electrodesand the tissue surface.

FIG. 7B illustrates a reverse “S” shape formed by the RF ablation probe38, which is inserted via the aperture 94 into the atrium 96. The uppersurface of the probe 38 containing the electrodes 40 is bent to conformwith the contoured inner surface of the atrium 96 and in particular, totake account of the protruding, irregularly shaped mass of tissue 98. Inthis manner, a full, solid contact is formed between the flat electrodes40 and the tissue to be ablated. FIG. 7C likewise illustrates anirregularly shaped surface 100 formed in the opposite wall of theatrium. The probe 38 is shown formed into an exaggerated “L” shape witha bend formed in the lower leg of the “L” to conform with the protrudingsurface 100.

In this manner, a number of elongated lesions can be formed within theinterior surface of the atrium 96, as indicated schematically by solidlines 102 in FIG. 7D. It will be appreciated by one skilled in the artthat the lines 102 represent linear transmural lesions in the interiorsurface of the atrium 96 as produced in accordance with the use of themalleable probe 38 to ablate endocardial tissue as shown in FIGS. 7B and7C. Likewise, the bendable, adaptable RF ablation probe can used toproduce elongated, thin lesions from the epicardial surface.

SECOND EMBODIMENT

FIGS. 8 to 10 illustrate side elevation, top plan and cross-sectionalfront elevation views of an RF ablation probe according to the secondembodiment of the invention. The RF ablation probe 60 comprises ahollow, substantially tubular body 58 made of teflon plastic, a numberof flat, conductive electrodes 50, and a malleable core 54 (not shown inFIGS. 8 and 9) contained within the centre of the thermally andelectrically insulative body 58. In particular, the teflon body 58 has arelatively rigid yet bendable structure and is capable of beingpermanently formed to have a particular shape. As indicated in FIG. 8,the upper surface of the distal end of the tubular body 58 is crimped toproduce a flat surface. The electrodes 50 are arranged on the flat uppersurface, and again are separated by thermally and electricallyinsulative material.

The electrodes 50 have a like construction to those describedhereinbefore with reference to the first embodiment. The flat uppersurface of the tubular body 58 provides a complementary surface to thatof the underside of each of the electrodes 50 and thereby ensures asolid connection between the two surfaces. Adhesive such as abio-compatible epoxy resin is preferably used to bond the undersurfaceof each electrode 50 with the upper flat surface of the tubular body 58.

Still further, it is preferable to weld or incorporate prongs or teeth56 capable of being bent to the under surface of each electrode 50. Withreference to FIG. 10, such prongs or teeth 56 rigidly connected to theunder surface of an electrode 50 can be used to puncture the tubularbody 58 when the electrode 50 is pressed into contact therewith. Oncethe teeth or prongs 56 are inserted through the tubular body 58 so thatthe electrode 50 is in direct contact with the surface of the tubularbody 58, the teeth or prongs 56 are bent within the interior of the body58 to rigidly interconnect the electrode 50 and the tubular body 58.This may be done in addition to applying adhesive between the lowersurface of the electrodes 50 and the tubular body 58.

With a malleable core 54, preferably made of copper, inserted within theinternal cavity of the tubular body 58, the internal cavity may then befilled with a sufficiently bendable matrix 52. Preferably, a rubber likespongy matrix 52 made of SILASTIC (trade mark) or the like is used. Itwill be apparent to a person skilled in the art, however, that otherbendable materials can be used without departing from the scope andspirit of the invention.

The RF ablation probe 60 according to the second embodiment may bepracticed in numerous ways including the exemplary manner describedhereinbefore with reference to FIGS. 7A to 7D. The second embodiment isadvantageous in that it provides a linear arrangement of flat electrodescapable of producing an elongated lesion in a malleable probe structurehaving a memory function. In particular, the probe may be bent or shapedto conform with an irregular or contoured surface and retain such shape.

THIRD EMBODIMENT

FIGS. 11 to 13 illustrate an RF ablation probe 70 according to a thirdembodiment of the invention. Again, a number of flat electrodes 80 arearranged at predetermined spaces on a top surface of an elongate probebody 82. The body of 82 of the probe is tubular and preferably made of arubber or soft plastic materials, such as SILASTIC, which is thermallyand electrically insulative. Electrical conductors or leads connected toeach electrode 80 are not shown in FIGS. 11 to 12 to simplify thediagram.

In this embodiment, rather than having an internal malleable core, arigid, pre-formed or shaped insert member 84 is inserted into theinternal cavity of the tubular body 82 at its distal end to thereby givethe probe 70 a corresponding pre-formed shape. The insert member 84 inthis example has an S-shape. In FIGS. 11 and 13, the pre-formed, rigid,cylindrical insert member 84 is preferably made of stainless steel or arigid plastic body and can be inserted into the interior cavity of thebody 82 to thereby give the probe 70 a corresponding S-like shape. Forexample, pre-formed insert members 84 can be made to complement the formof known tissue bodies. Alternatively, the insert member 84 can take theform of a deformable material, allowing a surgeon to customise its bentshape prior to use.

Using such pre-defined inserts 84, the flexible probe 70 is providedwith a pre-determined shape so as to conform the probe 70 to that shape.The probe 70 can be used to produce linear lesions.

FOURTH EMBODIMENT

FIGS. 14 and 15 illustrate a forth embodiment of an RF ablation probe110 for producing elongated, thin linear lesions in a tissue. In thisembodiment, the probe 110 consists of a solid, rigid body 112,preferably having an S or L-shaped terminal region 114 at the distalend. The upper surface of the distal end 114 of the probe 110 isprovided with a flat surface. An elongated, flat conductive electrode116 is provided on the flat surface, and preferably has a rectangularshape.

The body 112 of the probe 110 is preferably made of a rigid materialsuch as metal coated with an appropriate insulative material.Alternatively, the probe can be made of plastic and contain electricalconductors preferably internally connected to the electrode 116. RFenergy can be delivered to tissue in contact with the electrode 116.Further, the temperature of the electrode in contact with tissue can besensed using a thermocouple or other temperature sensing deviceconnected therewith. Still further, the electrode 116 may be used fordetecting or mapping electrical activity in the tissue contacting theelectrode 116.

This probe 110 can be used to produce linear, elongated transmurallesions in endocardial and epicardial tissue, and is able to apply ortransfer significant pressure between the electrode 116 and the tissuein contact therewith. This ensures that a solid contact is formed withthe tissue for delivery of RF energy to the tissue.

Only a small number of embodiments of the invention has been described.Changes and/or modifications obvious to one skilled in the art in viewof the specification can be made without departing from the scope andspirit of the invention.

1.-12. (canceled)
 13. A probe for ablating tissue, comprising: arelatively rigid body; at least one flat, elongate electrode formed in asurface of a distal portion of said rigid body; and at least oneelectrical conductor connected with said electrode for delivery of RFenergy thereto.
 14. A probe according to claim 13, wherein saidelectrodes are linearly arranged.
 15. A probe according to claim 13,further comprising a plurality of temperature sensing devices, each ofwhich is connected to a respective one of said plurality of electrodes.16. A probe according to claim 15, wherein at least two conductors ofsaid plurality of conductors are connected to each of said electrodes,and wherein one of said conductors comprises a thermocouple as saidtemperature sensing device.
 17. A probe according to claim 13, whereinone or more prongs are connected with each of the electrodes, whereinsaid one or more prongs is used to puncture said body and is capable ofbeing bent.
 18. A probe according to claim 13, wherein said body is madeof insulative material.